The invention relates to a reciprocating internal combustion engine including a crankshaft for actuating gas exchange valves and a crankcase vent, which is in communication with the engine intake ports by way of an oil separator.
In reciprocating piston internal combustion engines combustion gases enter the crankcase by way of the piston rings because of the reciprocating movement of the piston and he high gas pressure in the engine cylinders. These combustion gases which are also called xe2x80x9cblow-byxe2x80x9d gases increase the pressure in the crankcase. They detrimentally affect the lubricating oil and furthermore make it difficult to seal the crankcase. The crankcase is therefore vented. Generally, this is provided for by a connection between the crankcase and the engine air intake system. In this way, no emissions reach the environment. In order to keep the lubricating oil, which is contained in the crankcase gases in a finely distributed form, from the engine air intake system, oil separators are disposed in the communication line interconnecting the crankcase and the engine air intake system through which the crankcase gases are conducted before they enter the intake system and in which oil contained in the crankcase gases is separated from the crankcase vent gases.
Such a piston-type internal combustion engine is disclosed for example in U.S. Pat. No. 4,651,704. This publication discloses an internal combustion engine with a crankcase venting system and an oil separator wherein a hollow camshaft that is, more accurately, a camshaft with a bore extending therethrough is utilized as a separator for the heavy oil particles contained in the crankcase vent gases. From the bore extending axially through the camshaft radial bores lead to the space surrounding the camshaft. The axial bore is in communication with the air intake system by way of a breather space. In this particular engine, the camshaft is disposed above the gas exchange valves in the cylinder head of the engine. The surrounding space is in communication with the crankcase, so that the crankcase vent gases are conducted to the air intake system by way of the radial bores and the axial bore of the camshaft. Because of the high speed of the camshaft, the heavier oil particles contained in the vent gases are thrown outwardly out of the radial bores, whereas the lighter gas components flow, because of the pressure drop to the intake system, inwardly through the radial bores and the axial camshaft bore to the engine intake system.
It is the object of the present invention to improve the effectiveness of such an oil separation system.
In a reciprocating internal combustion engine in which a camshaft for actuating the gas exchange valves is disposed in a space, which is in communication with the engine crankcase to receive the vent gases therefrom, and the camshaft includes an axial passage and at least one radial bore and the axial passage is in communication with the engine intake duct for drawing vent gases from the crankcase to the engine intake duct through the camshaft, a disc provided with a radial disc bore is mounted onto the camshaft such that the disc bore is in alignment with the radial camshaft bore and the disc has an axial bore extending therethrough so as to intersect the radial disc bore adjacent the circumference of the disc, whereby vent gases entering the axial disc bore are accelerated in the axial bore and, upon entering the radial bore, oil particles are discharged outwardly through the radial disc bore while the gases flow inwardly through the radial disc bore to the camshaft passage and to the engine intake duct.
It is essential in accordance with the invention that the centrifugal forces acting or the vent gas and the oil particles when entering the radial bores are relatively high in order to greatly improve the separation effect in the radial bore extending now through the disc mounted on the camshaft. The disc can be formed integrally with the camshaft or it can be a separate component, which is mounted onto the camshaft by pressing, clamping, bolting cementing, brazing or welding.
The axial bore may extend centrally through the camshaft if the camshaft bearings are lubricated from without. If the camshaft bearings are lubricated by way of lubricant passages extending through the camshaft, the axial vent bore extends somewhat displaced radially, with respect to the lubricating oil passage, both systems being strictly separated from each other.
The disc includes, in addition to the radial bore, at least one bore, which extends parallel to the camshaft axis and intersects the radial bore. The crankcase vent gases which enter through this parallel bore are accelerated in the parallel bore and are separated by the centrifugal forces, so that, when reaching the radial bore, the oil particles are thrown outwardly whereas the vent gases, free of any oil particles, flow inwardly to the lower pressure axial crankshaft bore and from there to the engine intake system.
The invention will be described below in greater detail on the basis of the accompanying drawings, which show the state of the art and the arrangement according to the invention in a side-by-side comparison.